I'm thinking about whether I should unsolder both electrolytic capacitors or cut them off with side cutters. Since some of the soldering points are so corroded that the solder is no longer visible, I do both.
Here the right electrolytic capacitor is already missing a leg:
The close-up shows the destructive effect of the leaked electrolyte.
Conductor tracks and solder joints are eaten away by corrosion and one day little or no current flows through them. Then the camera fails completely or partially.
After all, it has lasted for 40 years so far. That deserves respect:
As you work on the spot, parts of the deposits crumble onto the work mat. The Swiffer is already there and cleans up:
Back to the treatment chair
The workplace:
The electrolytic capacitors are now removed.
You can see the corroded solder joints and partially corroded conductor tracks.
One cable is still soldered on:
The cable is unsoldered and returns to its original place later when the new electrolytic capacitors are soldered in.
When cleaning the area it would only get in the way:
The electrolytic capacitor on the prism is quickly unsoldered; the two soldering points are directly and freely accessible.
The process:
- Tin the soldering tip with solder for the best possible heat transfer,
- put some flux on the soldering points,
- hold the tip to the soldering points successively and first pull one and then the other leg out of the liquid solder.
- The shorter it takes, the better.
- After all, it's 340 degrees Celsius (= 644 F) at the soldering tip and electronic components and conductor tracks don't like heat that much.
Unfortunately, there was no picture of the process itself today because no camera hand was free.
But here is the result, the electrolytic capacitor is gone:
Here they lie now, the electrolytic capacitors that were hunted down.
In my enthusiasm, I didn't pay attention to which electrolytic capacitor belongs to which position in the camera and how the polarity is determined (an electrolytic capacitor is a polarized electronic component with a plus and a minus connection; it must be connected correctly).
But this is important because every electrolytic capacitor has a different value.
Good thing I took photos before for orientation.
The Minolta service manual for the XG-M also provides information about this in the layout view of the circuit:
The cleared circuit board with the corroded passages.
This needs to be cleaned as best as possible. Otherwise the mess will continue:
I'm trying a few cleaning methods. Knowledge of chemistry would be helpful now - what solves what?
Circuit board cleaner and isopropyl alcohol don't work, so my only option is the mechanical route with the circuit board tool and the fiberglass pen.
And that's not a safe thing to do, because when the deposits are scraped off the sensitive and thin conductor tracks, damage can quickly occur. But I have no other choice.
Today I would remove the battery acid residue with Durgol descaling solution and then Aqua purificata. Others use vinegar. It is important that everything is removed so that the corrosion does not progress. The Dremel Stylo with stainless steel brush does also a good job.
Here the result. The corrosion is almost completely removed. Unfortunately also a part of the outer conductor track, at least that's what it looks like
That's called collateral damage:
The continuity tester on my multimeter provides certainty.
To do this, the measuring tips of the device are stopped before and after the damaged area.
The device creates a low measuring voltage between the tips.
If the conductor track is intact, current flows and the device beeps.
If not, then there is either too little current or no current at all.
And that's how it is in this case - the conductor track no longer conducts.
But you always have to think carefully about what you are measuring.
In complex circuits like this, the current can travel over many paths because there are many connections and branches. A continuity may then be detected where there is none because the current has found a better path.
In this case it should be clear. One measuring tip is basically at the end of the line, the current can only run through the part to be tested to the second measuring tip, there is no other way.
Nothing is happening here:
I have now given up the habit of self-blame
Because without intervention, the camera would sooner or later become inoperable and the damage to the circuit board would become greater. „Best possible“ in treatment means „best possible“ and not „optimal“.
But there is a solution: the damaged passage is bridged, a new conductor is pulled and the current can flow again.
For this I need a cable that is as thin as possible because I don't want to cram anything thick into it. It would also make the soldering points larger and so there is the risk of an unwanted connection between two adjacent conductor tracks during soldering.
I found what I was looking for in an abandoned Nikon MD-4 Motor Drive for the F3, which I had opened for studying purposes.
The donor cable is removed using side cutters:
